WO 90/00434 discloses an annular flange between the first and second threaded section of the screw-in component. An annular seal may be supported on the annular flange and brought into contact by its other annular surface with the screw-on fixing component of the filter medium. The fixing component is provided on its outer circumference with setscrews positioned diametrically opposite each other to facilitate the screw-on process. The opposite side of the filter medium is fixed to a second fixing component. The second fixing component also has on its outer circumference screw-in openings positioned diametrically opposite each other for applying a fixing tool, so that it is possible to use the fixing tool and the auxiliary fixing means in the form of the setscrews to carry out a screw-on application process potentially free of torsion. In this way, the filter medium, in particular, one in the form of metal wool, is kept free of torsional stresses for later polymer melt filtration, and avoids damaging the support grid enclosing the metal wool filter medium to shield it from the exterior. The volume displacement component is then screwed onto this fixing component in the direction of the supporting tube. While this disclosed solution does make it possible to replace a fouled filter medium with a new filter element having fixing components and to leave the valuable stainless steel components in the form of the screw-in component and the supporting tube at the place of assembly, the assembly process itself is difficult to carry out because of insufficient rigidity of the filter element structure which complicates the replacement process. The possibility of buildup of torsional stresses in the support grid and in the filter medium in the fixing processes, make failure possible, especially in a high-pressure application.
DE 43 43 270 A1 discloses a spinning head for spinning polymer melts, having an upper element and a nozzle block housing with a nozzle plate having a maximum area of 90 cm2 and a melt channel with filter cartridge. As disclosed, a single filter cartridge is mounted upstream in the direction of flow from each nozzle plate. The filter cartridge has a seamless wire cloth cylinder through which flow proceeds radially from the exterior toward the interior. The cylinder has a cap at the upper end and a connecting piece tapering downward through which melt is conducted at the lower end. The zone of the melt channel receiving the filter cartridge is configured as a cone, at least in the lower third. The tapering connecting piece of the filter cartridge is pressed into the cone by the polymer melt so as to be self-sealing. Uniform flow of the polymer melt with dead spaces eliminated is achieved to the greatest extent possible. A volume displacement component, which is a one-piece component of a supporting tube for the filter medium, is provided at the upper end of the filter cartridge, opposite the lower end of the cone referred to. Despite the resulting reinforcement of the system as a whole, susceptibility to torsional stresses is still present. On the whole, the process of filter element replacement is accomplished only with difficulty. Virtually complete disassembly of the disclosed spinning head is required for the purpose.
WO 01/52966 A1 discloses a filter device with a filter housing having a filter admission and filter discharge, as well as a filter element dividing a filter chamber into two component chambers. Since one component chamber narrows in cross-section from the filter admission toward the filter discharge, a conical configuration of at least one of the two component chambers separated by the filter element is provided. This configuration permits achievement of optimal dwell time distribution inside the filter device, along with a uniform rate of flow, a characteristic which performs an essential function, especially in the case of high-viscosity fluids such as polymer melts. A fixing component configured as a handle encircles the volume displacement component in the interior. Since the filter medium surrounding the supporting tube rests on the fixing component and at the opposite end in receptacle components is rigidly connected to the housing, the harmful torsional stresses described also arise in a process of disassembly and replacement of the filter element. Replacement of the filter elements also entails high cost.